1. Field of the Invention
The present invention relates to a plasma display panel used for a flat television set, an information display or the like, and a plasma display apparatus having the same. More particularly, the invention relates to an AC in-plane discharge plasma display panel capable of providing high-definition and bright displaying, and a plasma display apparatus having the same.
2. Description of the Related Art
The plasma display apparatus is designed to perform displaying by using ultraviolet rays generated by gas discharge to excite a phosphor to emit a light, and expected to be applied to a large-screen television set, an information display or the like. A variety of systems have been developed for a color plasma display apparatus, and an AC in-plane discharge plasma display is advantageous because of its luminance, easy panel manufacturing, and so on. FIG. 1 is a schematic view showing the structure of a typical AC in-plane discharge color plasma display panel of a reflection type. FIG. 2A is a schematic view showing a positional relation among a scanning electrode, a maintenance electrode and a bus electrode in the conventional color plasma display panel. FIG. 2B is a schematic view showing a positional relation between a partition wall and a data electrode in the conventional color plasma display panel.
In a front substrate 100 as a display side substrate, a plurality of strip transparent electrode films 3 and narrow strip bus electrodes 4 are formed in parallel as in-plane discharge electrodes on a glass substrate 1. For the transparent electrode film 3, an ITO thin film or a tin oxide thin film can be used. To supply a sufficient discharge current for the light emission of a large-area panel, however, the electrical resistances of these thin films are too large. Accordingly, the metallic bus electrode 4 having high electrical conductivity is provided. For such a bus electrode 4, an electrode made of, for example, a thick silver film or a metallic thin film containing copper, aluminum, chromium or the like may be used. A dielectric layer 7 is formed over the bus electrodes 4. In general, the dielectric layer 7 is formed in the following manner. That is, first, low melting point glass paste is coated on the transparent electrode film 3 having the bus electrode 4 formed, and by baking this film at a high temperature, a transparent glass layer having a thickness of about 20 to 40 xcexcm and high withstand voltage is formed. Then, a magnesium oxide thin film having a high secondary electron emission coefficient and a high sputtering resistance is formed as a surface protective layer on the glass layer.
On the other hand, in a backside substrate 200 disposed in parallel with the front substrate 100, a plurality of strip data electrodes 5 and a dielectric layer 10 covering these data electrodes 5 are formed on a glass substrate 2. A main component contained in the dielectric layer 10 is low melting point glass. On the dielectric layer 10, a belt-like partition wall 6 is formed to be extended in a vertical direction (columnar direction). The partition wall 6 is a structure having a width set in a range of about 30 to 120 xcexcm, and a height set in a range of about 80 to 150 xcexcm. This structure is generally made of a mixture of oxide powder such as alumina or the like, and low melting point glass. On the bottom portions and the side faces of a plurality of grooves defined by the partition walls 6, phosphor layers 9 each made of powdered phosphor to emit a red, green or blue light are coated. The colors of lights emitted from the phosphor layers 9 are arrayed in a horizontal direction (line direction) in the above order.
Then, the backside substrate 200 and the front substrate 100 are combined together, the peripheries of both substrates are sealed with frit glass and, after the execution of heating and exhaustion, discharge gas containing rare gas as a main component is sealed therein. In this way, the color plasma display panel is constructed.
The partition wall 6 serves to secure discharge space, and prevent crosstalk and the color blotting of an emitted light during discharging.
In the front substrate 100, in-plane discharge electrodes make a pair sandwiching an in-plane discharge gap 11. That is, one is an in-plane discharge electrode (scanning electrode) 13, and the other is an in-plane discharge electrode (maintenance electrode) 14. Then, the conventional color plasma display panel is driven for displaying by applying various voltage waveforms to three kinds of electrodes, i.e., the electrodes 13 and 14, and the data electrode 5 provided in the backside substrate 200.
FIG. 3 is a timing chart showing a driving waveform applied to each electrode when the scanning electrode of the n-th line is designed as Sn, the maintenance electrode is designed as Cn, and the data electrode is designed as Dj.
Scanning pulses are sequentially applied to the scanning electrodes Sn, Sn+1, Sn+2, Sn+3, and so on. In matching with this timing, a data pulse having polarity reverse to that of the scanning pulse is applied to the data electrode Dj according to the display data of a display cell on each of the scanning electrodes. Accordingly, inter-plane discharging occurs between each of the scanning electrodes Sn, . . . and so on, and the data electrode Dj. By a writing operation performed based on such inter-plane discharging, positive wall charges are generated on the surface of each of the scanning electrodes Sn, . . . and so on. In the display cell having the wall charges generated, subsequently, in-plane discharging occurs by a maintenance pulse applied between the maintenance electrodes Cm (Cn, Cn+1, . . . and so on) and each of the scanning electrodes Sn, and so on.
On the other hand, in a display cell having no wall charges generated and no writing performed therein because of the application of no data pulses and the occurrence of no discharging between the data electrode and the scanning electrode, no maintenance discharging occurs even when a maintenance pulse is applied. This is because of the lack of an electric field superposition effect provided by wall charges.
Then, light emission and displaying are carried out by applying the maintenance pulse to the display cell having the wall charges generated by a specified number of times.
For the maintenance electrode Cm, it is not necessary to apply a pulse selected for each piece unlike the case of the scanning pulse. Thus, the respective maintenance electrodes Cm are connected in common and, as shown in FIG. 3, the same voltage waveform is applied thereto. In addition, in a practically used panel, in order to improve the operability of writing, a preparation sequence has been employed for the purpose of Activation inside the display cell and the generation of proper wall charges, which is achieved by applying high voltages to all the display cells prior to a writing operation, and executing a preparation discharging operation for forcible discharging, or the like.
A sub-field method has been employed for the gradational displaying of the AC plasma display. This is due to the fact that in the AC plasma display, the voltage modulation of emitted light displaying luminance is difficult, and the number of light emission times must be changed for luminance modulation. The sub-field method is designed to reproduce a multilevel image by breaking down the multilevel image into a plurality of binary display images and executing continuous displaying at a high speed so as to obtain a visual integration effect.
Such a conventional in-plane discharge AC plasma display has an excellent characteristic. However, as can be understood from the structure of the in-plane discharge electrode shown in FIG. 1, two in-plane discharge electrodes making a pair are necessary for the light emission of one display line. An in-plane discharge gap between such in-plane discharge electrodes is relatively narrow, i.e., in a range of about 50 to 100 xcexcm. Regarding a non-discharge gap provided between display lines adjacent to each other in the vertical direction, a width larger by three times or more than the in-plane discharge gap is necessary to avoid discharge crosstalk. In addition, for the metallic bus electrode 4, a width of about 100 xcexcm is necessary because of a material specific resistance and a limitation placed on the manufacturing technology of a large-area panel. Such a limitation causes reductions in the area and the numerical aperture of the in-plane discharge electrode as a pixel pitch is narrowed to increase resolution. Consequently, it is difficult to realize high luminance.
In addition, because of an increase in the number of scanning lines following higher resolution, there is a need to shorten the time of scanning required for the writing of one display line. In the case of a typical television set and the VGA class having 480 lines, full-color displaying by the sub-field method can be performed. However, there has been a big problem inherent in the case of a high-definition television (HDTV) set and a high-resolution display each having the number of scanning lines set equal to about 1000. Specifically, the time of scanning becomes extremely short, making a sure operation difficult and causing writing failures or erroneous lighting. Consequently, good displaying cannot be carried out.
Thus, for the purpose of increasing the area and the numerical aperture of the in-plane discharge electrode, there has been proposed a color plasma display panel, comprising a partition wall extended in a horizontal direction and a bus electrode provided thereon. Hereinafter, this color plasma display will be referred to as a second conventional art, and the foregoing conventional color plasma display panel as a first conventional art. FIG. 4A is a schematic view showing a positional relation among a scanning electrode, a maintenance electrode and a bus electrode in the second conventional art; and FIG. 4B a schematic view showing a positional relation between a partition wall and a data electrode in the second conventional art.
In the second conventional art, as shown in FIG. 4A, an in-plane discharge electrode provided in the front substrate is composed of a wide transparent electrode 15 extended in a horizontal direction, and a bus electrode 16 disposed in the center part of the transparent electrode 15. Also, as shown in FIG. 4B, a partition wall 17 is composed of a horizontal partition wall 17a extended in a horizontal direction, and a vertical partition wall 17b for further defining a groove defined by the horizontal partition wall 17a into a plurality of display cells. Between adjacent display lines, however, the position of the vertical partition wall 17b is shifted by half a display cell. In other words, between the display lines adjacent to each other, the display cells are arranged in a triangular pattern. Then, the panel is assembled such that the bus electrode 16 can overlap the horizontal partition wall 17a when seen from the plane.
In the second conventional art constructed in the foregoing manner, a so-called double side in-plane discharge electrode structure is employed, where one in-plane discharge electrode is placed over two upper and lower display lines adjacent to each other. Compared with the first conventional art shown in FIG. 2A, there are no light shielding or non-discharge gaps caused by the bus electrode. Accordingly, the effective area and numerical aperture of the in-plane discharge electrode are larger.
In addition, as shown in FIG. 4B, data electrodes 18 are stitched alternately one each among the display cells. Thus, irrespective of the double side in-plane discharge electrode structure, even by driving of a waveform similar to that shown in FIG. 3, each display cell may be independently selected and writing can be carried out.
However, in the case of the triangular arrangement of the display cells, compared with a stripe arrangement like that in the first conventional art, there are problems including slightly worse color mixing, a little lower sharpness of character displaying, and so on. Also, in the second conventional art, if the number of display lines is set equal to, e.g., 480, 480 scanning electrodes and 480+1 maintenance electrodes are necessary. Consequently, it is difficult to realize a high-definition and high-resolution plasma display panel such as HDTV. Further, since the display cells are completely partitioned by the partition walls 17a and 17b to prevent discharge crosstalk, exhaust conductance is extremely small in the manufacturing process. Thus, it may take a long tine for exhaust processing, or deterioration may occur in a panel characteristic because of residual impurities. Especially, in the large-area and high-definition panel, such a problem tends to be more serious.
Yet another color plasma display panel has been proposed, the structure of which is simplified by adding a change to the driving method (Japanese Patent Laid-open Publication No. Hei 11-65518). Hereinafter, this conventional color plasma display panel will be referred to as a third conventional art. FIG. 5A is a schematic view showing a positional relation among a scanning electrode, a maintenance electrode and a bus electrode in the third conventional art; and FIG. 5B a schematic view showing a positional relation between a partition wall and a data electrode in the third conventional art.
In the third conventional art, the transparent electrode and the bus electrode constituting the maintenance electrodes Cm of the second conventional art are eliminated, and the vertical dimension of a transparent electrode 19 constituting each of scanning electrodes Sn, Sn+1, Sn+2, Sn+3, and so on, is set larger. A partition wall 22 is in a parallel cross shape, and display cells defined by the partition wall 22 are arranged in a stripe pattern.
In the third conventional art constructed in the foregoing manner, if the number of lines is 480, then the necessary number of in-plane discharge electrodes is 480+1. Also, as can be easily understood from FIGS. 5A and 5B, the area of an in-plane discharge electrode directly related to emitted light luminance per unit display area can be set larger than those in the first and second conventional arts. Thus, since the number of in-plane discharge electrodes can be reduced and the area of an in-plane discharge electrode can be increased, the third conventional art is very advantageous especially for the high-resolution and high-definition plasma display panel having a number of scanning lines.
However, though the third conventional art achieves the intended object, the display panel must be operated by a special interlaced driving method, and there is a problem of a small operation margin. In addition, as in the case of the second conventional art shown in FIG. 4B, because of the partitioning of the respective display cells by the partition wall 22, exhaustion takes a long period of time in the manufacturing process, and it is difficult to obtain intra-surface uniformity of a panel characteristic. Consequently, there remains a difficulty of practical use.
It is an object of the present invention to provide a plasma display panel capable of performing high-resolution and high-definition displaying by obtaining a large area and a large numerical aperture for an in-plane discharge electrode, and securing a large operation margin. It is another object of the invention to provide a plasma display apparatus having such a plasma display panel.
According to one aspect of the present invention, a plasma display panel comprises first and second substrates are disposed oppositely to each other in a plasma display panel. The plasma display panel further comprises a parallel-crossed partition wall, a plurality of bus electrodes, a plurality of display discharge electrodes, and a plurality of data electrodes. The parallel-crossed partition wall defines a space between the first and second substrates into a plurality of display cells. The bus electrodes are provided in a side of the first substrate opposite the second substrate, and superposed on a portion of the partition wall extended in the line direction when seen from a plane. The display discharge electrodes each are extended from each of the bus electrodes in each of the display cells defined in the columnar direction by a portion of the partition wall overlapping with the bus electrode when seen from the plane. The data electrodes are provided in a side of the second substrate opposite the first substrate and extended in the columnar direction.
According to the aspect of the present invention, the bus electrode is superposed on the portion of the partition wall extended in the line direction when seen from the plane, and the display discharge electrode is extended from each of the bus electrodes, when seen from the plane, in each of the display cells defined in the columnar direction by the line-direction extended portion of the partition wall overlapping with the bus electrode. Thus, no discharge interference occurs between the display cells adjacent to each other in the line direction. In addition, the bus electrode is shared by the display cells making a pair, which are defined in the columnar direction by the line-direction extended portion of the partition wall. Thus, even without employing a complex interlaced driving method, high-density and highly accurate displaying can be easily carried out by a three-phase scanning method or the like, which will be described later.
Therefore, it is possible to realize high emitted light luminance and high light emission efficiency. The invention is particularly advantageous for a high-resolution and high-definition panel, and it is possible to manufacture a high performance HDTV set and a high-resolution display at low costs.
According to another aspect of the present invention, a plasma display apparatus comprises the pre-described plasma display panel and a driving device. The driving device applies AC pulses to two display discharge electrodes provided in each of the display cells after execution of writing discharge between the data electrode and the other display discharge electrode in the display cell.
According to another aspect of the present invention, a plasma display apparatus comprises the pre-described plasma display panel and a driving device. The driving device applies a scanning pulse to one of the bus electrodes, first and second voltages different from each other to two of the bus electrodes adjacent to the bus electrode which is applied of the scanning pulse during a scanning period, and then applied AC pulses to two display discharge electrodes provided in each of the display cells.
In these plasma display apparatus, emitted light display is carried out by applying AC pulses to two display discharge electrodes.
According to another aspect of the present invention, a plasma display apparatus for performing interlaced displaying by setting an odd-numbered field and an even-numbered field comprises the pre-described plasma display panel and a driving device. The driving device applies a scanning pulse to odd-numbered ones from the top of the bus electrodes, and maintenance pulses being identical and different in phase for every two adjacent ones of the bus electrodes after applying the scanning pulse to all the odd-numbered bus electrodes, in the case of displaying of the odd-numbered field. The driving device also applies a scanning pulse to even-numbered ones from the top of the bus electrodes, and maintenance pulses being identical and different in phase for every two adjacent ones of the bus electrodes after applying the scanning pulse to all the even-numbered bus electrodes, in the case of displaying of the even-numbered field.
In the plasma display apparatus, emitted light displaying is carried out for a display line of an odd-numbered field, writing having been executed therein, by applying maintenance pulses being identical and different in phase for every two adjacent bus electrodes after applying the scanning pulse, Also, emitted light displaying is carried out for a display line of an even-numbered field, writing having been executed therein, by applying maintenance pulses being identical and different in phase for every two adjacent bus electrodes after applying the scanning pulse. Accordingly, emitted light displaying is carried out on the full surface of the panel.
According to another aspect of the present invention, a plasma display apparatus for performing interlaced displaying by setting an odd-numbered field and an even-numbered field comprises the pre-described plasma display panel and a driving device. The driving device applies a scanning pulse to odd or even-numbered ones from a top of the bus electrodes, and maintenance pulses being identical and different in phase for every two adjacent ones of the bus electrodes after applying the scanning pulse to all the odd or even-numbered bus electrodes, in the case of displaying of the odd-numbered field. The driving device also applies a scanning pulse to even or odd-numbered ones from the top of the bus electrodes, and a data pulse to the data electrode based on display data of a display line shifted by one, and maintenance pulses being identical and different in phase for every two adjacent ones of the bus electrodes after applying the scanning pulse to all the even or odd-numbered bus electrodes, in the case of displaying of the even-numbered field.
In the plasma display apparatus, emitted light displaying is carried out for odd-numbered display lines by applying maintenance pulses being identical and different in phase for every two adjacent bus electrodes after applying the scanning pulse. Also, emitted light displaying is carried out for even-numbered display lines by applying maintenance pulses being identical and different in phase for every two adjacent bus electrodes after applying the scanning pulse. Accordingly, emitted light displaying is carried out on the full surface of the panel.
According to another aspect of the present invention, a plasma display apparatus for performing interlaced displaying by setting an odd-numbered field and an even-numbered field comprises the pre-described plasma display panel and a driving device. The driving device applies a scanning pulse to odd-numbered ones from the top of the bus electrodes, and mutually reversed AC maintenance pulses to two adjacent ones of the bus electrodes after applying the scanning pulse to all the odd-numbered bus electrodes, in the case of displaying of the odd-numbered field. The driving device also applies a scanning pulse to even-numbered ones from the top of the bus electrodes, and mutually reversed AC maintenance pulses to two adjacent ones of the bus electrodes after applying the scanning pulse to all the even-numbered bus electrodes, in the case of displaying of the even-numbered field.
In the plasma display apparatus, emitted light displaying is carried out for two adjacent display lines having a display discharge electrode extended from an odd-numbered bus electrode from a top by applying mutually reversed AC maintenance pulses to two adjacent bus electrodes after applying the scanning pulse. Also, emitted light displaying is carried out for two adjacent display lines having a display discharge electrode extended from an even-numbered bus electrode from the top by applying mutually reversed AC maintenance pulses to two adjacent bus electrodes after applying the scanning pulse. Accordingly, emitted light displaying is carried out on the full surface of the panel.